Neurostimulation is a treatment method utilized for managing the disabilities associated with pain, movement disorders such as Parkinson's Disease (PD), dystonia, and essential tremor, and also a number of psychological disorders such as depression, mood, anxiety, addiction, and obsessive compulsive disorders. Deep brain stimulation systems deliver stimulation to a patient's brain.
At least some known deep brain stimulation (DBS) systems include a plug that mounts to a burr hole formed in the patient's skull. A lead including stimulation electrodes is coupled to the plug. The plug includes mechanical features (e.g., a clamping mechanism) that lock the lead in place over an exit point from the patient's brain. The lead exits the brain, and is coupled to a stimulation device (e.g., an implantable pulse generator) via an extension. The stimulation device may be located, for example, in the patient's chest.
For example, FIG. 1 is a schematic view of a known deep brain stimulation system 100. System 100 includes a plurality of DBS leads 102 electrically coupled to a stimulation device 104 using associated extensions 106. As indicated by a region 108, when stimulation device 104 functions as an indifferent electrode for DBS leads 102 in a unipolar configuration, DBS leads 102 and stimulation device 104 form a relatively large current loop. During magnetic resonance imaging (MRI) scans, magnetic flux through the current loop due to MRI gradient fields can generate unintended current flow through extension 104 and/or DBS leads 102. This unintended current flow may result in electrical stimulation being applied by DBS leads 102 that exceeds target stimulation thresholds.